The present invention relates to communications networks and more specifically to failure response in communications networks.
Failures in communication networks, such as a fiber cut, require rapid response to prevent data loss and network slowdown. Optical Carrier (OC) links, such as OC-12, OC-48, and OC-192 carry high speed data across communications networks. As many as 160 OC Links can be compressed onto a fiber by a Dense Wavelength Division Multiplexer (DWDM), resulting in data transfer speeds as high as 1.6 trillion bits per second (Tbps). The high rate of data transfer requires efficient solutions to problems in transmission, such as breaks or equipment failure.
Accordingly, the data traffic is rerouted via an alternate path when a failure occurs. The data traffic can either be routed to another router or another DWDM. Routing traffic to another router can take between a few seconds and several minutes. Given the speed of the data traffic, rerouting to another router is not practical. Furthermore, even though rerouting to different DWDM is achieved at reasonable speeds (50 ms), data traffic cannot be rerouted when the cut occurs between the router and the DWDM.
To respond to failures between the router and the DWDM, additional links and routers are used. For example, a router may include a working port for transferring data and a protection port. Alternately, a router may be associated with a backup router for transferring data when the router fails. Optical Cross-Connect Systems (OXCs), include a Spare Physical Layer and a Spare Service Layer to be used during network failures. If a failure occurs between two OXCs, one OXC detects the failure and transmits the data using the Spare Physical Layer. If a failure occurs between the router and the OXC, the router detects the failure and the data is transmitted using either the protection port or the backup router. The protection port or backup router is connected by the OXC to the Spare Service Layer.
The extra capacity allows for fast restoration of the fiber optic network, but would result in very high costs due to adding the protection port and the Spare Physical Layer and the Spare Service Layer. For example, the costs of allocating additional resources is estimated to exceed $10 billion. Accordingly, what is needed is a system and method for restoring network failures quickly with minimal costs.